Industry increasingly depends upon highly automated data acquisition and control systems to ensure that industrial processes are run efficiently, safely and reliably while lowering their overall production costs. Data acquisition begins when a number of sensors measure aspects of an industrial process and periodically report their measurements back to a data collection and control system. Such measurements come in a wide variety of forms. By way of example the measurements produced by a sensor/recorder include: a temperature, a pressure, a pH, a mass/volume flow of material, a tallied inventory of packages waiting in a shipping line, or a photograph of a room in a factory. Often sophisticated process management and control software examines the incoming data, produces status reports, and, in many cases, responds by sending commands to actuators/controllers that adjust the operation of at least a portion of the industrial process. The data produced by the sensors also allow an operator to perform a number of supervisory tasks including: tailor the process (e.g., specify new set points) in response to varying external conditions (including costs of raw materials), detect an inefficient/non-optimal operating condition and/or impending equipment failure, and take remedial actions such as move equipment into and out of service as required.
Typical industrial processes are extremely complex and receive substantially greater volumes of information than any human could possibly digest in its raw form. By way of example, it is not unheard of to have thousands of sensors and control elements (e.g., valve actuators) monitoring/controlling aspects of a multi-stage process within an industrial plant. These sensors are of varied type and report on varied characteristics of the process. Their outputs are similarly varied in the meaning of their measurements, in the amount of data sent for each measurement, and in the frequency of their measurements. As regards the latter, for accuracy and to enable quick response, some of these sensors/control elements take one or more measurements every second. When multiplied by thousands of sensors/control elements, this results in so much data flowing into the process control system that sophisticated data management and process visualization techniques are required.
Highly advanced human-machine interface/process visualization systems exist today that are linked to data sources such as the above-described sensors and controllers. Such systems acquire and digest (e.g., filter) the process data described above. The digested process data in-turn drives a graphical display rendered by a human machine interface. Such data includes mode changes, events, and alarm messages rendered by process controllers in response to a variety of detected process conditions/circumstances.
Process alarm messages are traditionally sent from plant control processors to alarm displays on workstations to notify operators of plant upsets. Generally, alarm messages are issued by control processors when a measured or calculated value is rendered outside a pre-configured range. The plant controller transmits the generated alarm to one or more operator workstations coupled to a separate (e.g., application) network. Detection, generation and transmission of alarms can potentially place a heavy load on a controller.
Known process control systems support a variety of alarm ordering techniques including assigning alarm priorities and filtering alarm messages according any of a variety of characteristics. The alarm prioritization/filtering functionality carried out by the control processor assists operators in assessing plant/process status and facilitates expedited correction of problems as they arise in a plant process. In general, the alarm priorities are relatively fixed and are changed through human intervention. Prioritizing alarms/messages alone will not avoid overwhelming an operator with a shower of alarm messages during a major plant failure or succession of cascading process/plant component failures. Overlooking a particular alarm or class of alarms, during an alarm shower can lead to harm to both humans and the plant itself.